Cause

The below mentioned workflow's is depreciated and no more available in our current version of LMS

"Access Simple Catalog Search"

"Access Browser Catalog Search"

"Access Community"

Resolution

This is expected behavior., Existing roles for which these workflows had been assigned will see these workflows in list of "Assigned" workflows.If we remove these workflow from existing role and then try to add back then you will not get them in list of "available" workflows anymore.